The Study Of Digital Three-dimensional Reconstruction For Normal Female Pelvis

Pelvis is an important part of the human body, and it is closely related to fertility and delivery for female. With the discovery of X-ray in1895, X-ray pelvimetry was widely used in clinical. Many countries and nations, including China, have completed the large scale research for local female pelvis in detail. Although X-ray pelvimetry was more advanced than manual pelvimetry with pelvic measuring instrument, deviation caused by the shooting position and posture, blind area of midpelvis photographs, restriction of planar photograph information and radiation exposure limited its clinical application. With the development and popularization of computer technology, digitalization applications in the medical field entered a new era in the late19th century. The core technology of digital medicine is three-dimensional(3D) reconstruction, which transform planar image data set of computer tomography(CT) and magnetic resonance imaging(MRI) into digital model of3D effect by using reverse engineering software.American Federle MP et al. first reported CT pelvimetry for female in1982. In2003, Balleyguier C and colleagues first reported3D pelvis model reconstruction through CT scan, and measured a part of pelvis diameter, they thought the3D pelvis model could be not only observed in every direction and measured accurately, but also more easily understood by clinicians and midwives. However, there is no large scale research on female pelvis physiological parameters by using CT pelvimetry techniques reported currently. In1985, Stark DD and colleagues first reported pelvimetry through MRI planar photograph, they concluded that MR pelvimetry is an accurate technique for obtaining traditional pelvimetric measurements without exposure to ionizing radiation and these techniques can be further used to investigate soft-tissue dystocia and obstructed labor. However, due to pelvis showed low signal in MRI, with the poor surrounding tissue contrast, it was too difficult to reconstruct. So far, there is very little relevant research, rarely3D reconstruction of part of the pelvis with MRI data reported, no complete pelvis reconstruction and measurement reported.We know significant differences of shape and size exist among different ethnic female pelvis. According to literature, the shape and size of the pelvis of the same ethnicity also vary with the time and living environment, and formation and development of female pelvis was affected by various factors such as climate, nutrition, diet and labor habits. Investigators from German and American found that anatomy of European female pelvis had changed in these more than20years. Therefore, an increase in cephalopelvic disproportion has to be expected. Chinese specialist Shuwen Wang et al. reported that pelvis diameter and type of multipara of fertility period had changed significantly in Tianjin from1955to1985. From1984to1992, led by Shuwen Wang, specialists of national cooperation group performed pelvimetry and analyzed pelvimetric data of6835female of fertility period, then study on Chinese female pelvis almost ceased in the nearly23to26years. As we all know, China has greatly changed in economy and culture, nutrition, lifestyle of Chinese people has also changed entirely. Therefore, we speculate that the shape and size of Chinese female pelvis seemed to change accordingly in these situations. At the same time, an increasing proportion of cesarean section in recent years was due to objective causes such as socio-economic factors, and subjective causes such as generous indications of cesarean section led by some clinicians’ inaccurate diagnostic criteria on relative cephalopelvic disproportion. Conventional method to study on pelvis has great limitations, external measurement commonly used in clinical can only help us evaluate pelvis indirectly, while internal diameter and pelvis type related to delivery were difficult to be analyzed. Though delivery process is related to force of labor, soft birth canal and size of fetal head, pelvis play an important role in it. And pelvis is relatively constant, the detailed ante partum pelvimetric diagnosis seems to be advisable.Therefore, this topic designed a research on normal Chinese female pelvis3D model construction and measurement from cadaver to in vivo with CT/MR data set combining with digital3D reconstruction techniques, providing a basis for a further better understanding of modern Chinese female pelvis information.Part one:The study of digital three-dimensional reconstruction for cadaver of normal femalea number of key technology and steps need to be master for the successful applying of digital three-dimensional reconstruction, which involves multidisciplinary knowledge. The use of software is often obscure and image data collection and storage are distinct from data storage of routine examination, such as CT and MRI. So in order to reconstruct and measure the pelvis, we have to process the female pelvic radiograph data by using multiple software. In order to grasp the construction of three-dimensional pelvic post production methods and techniques, we first select the virtual Chinese No.1female (VCH-F1) image database for our preliminary exploration of the reconstruction of digital female pelvis, which is made in2003and provided by the Southern Medical University Institute of anatomy. The body of a19-year-old,155.00centimetre tall and46.00kilogram weight from Guangxi, and died of food poisoning was used for the establishment of the database, with written consent from her relatives. The catalog number is VCH-F1(Virtual Chinese Human-female Number1). There are three original database, including Milling images data, CT data set, the MRI data set.Section1:materials and methodsOne:three-dimensional reconstruction based on the milling images data.1. data collectionThe specimen of VCH-F1was entrapped and refrigerated from the head to the whole body in a special laboratory and a total of8556dimensions was obtained. The layer thickness was0.22mm. This study selected the continuous tomographic images from the superior boder of the iliac crest(DSCF3100_pl.jpg) to the small rotor edge of the iliac crest(DSCF4500_pl.jpg)(pixel size:1512X1008), each2mm and a total of141pieces.2. image registration and segmentationBecause there will be a lot of interference information in the picture obtained by the high pixel camera, we should first complete a series of processing,such as calculating two-dimensional projective transformation parameter and registrating projective distortion by using photoshop pretreatment software and matlab7.0simulation software and outline the reconstruction target. In other words, the pelvic region in each picture on segmentation was marked out for computer recognition.3. three-dimensional reconstructionThe segmented image was input into the Mimics software. After the image positioning, image orgnizing and inerpolation processing, the reconstruction threshold of the bone was set, and we edit the image by using the Edit masks fuction of the Mimics software. Finally the digital three-dimensional model of female pelvis, including parts of lumbar spine and femur was reconstructed by regional growth fuction.Two:three-dimensional reconstruction of female cadaver based on the CT database1. software and equipmentVCH-F1data set, computer hardware, dual core processor, computer system: Windows XP Professional SP2operating system, three-dimensional reconstruction software(Mimics10.01), photoshop7.0image processing software, DICOM viewer, Somatom Plus4spiral CT.2. data collectionCT scan layer spacing was all1.0mm, and a total of1721layers were obtained. The pelvis sequence was229layers, and saved in DICOM format after making thin.3. pelvis three-dimensional reconstructionThe segmented image was input into the Mimics software. After the image positioning, image orgnizing and inerpolation processing, the reconstruction threshold of the bone was set, and we using Mimics software to modify the ischial spine and sacrum. Finally the digital three-dimensional model of female pelvis, including parts of lumbar spine and femur was reconstructed by regional growth fuction. Three:three-dimensional reconstruction of the female pelvis of cadaver based onMRI data set.1. software and equipmentThe soft device for MRI data reconstruction was the same to CT and MRI scanning apparatus was Siemens Magnetom Vision1.5T superconducting type scanner.2. data collectionThe MRI scan layer thickness was2.0mm, layer spacing0, TR/TE 800.0ms/l4.0ms, FOV430mm×430mm. All the data was saved in DICOM format.3. Image conversion and bone tissue segmentationThe MRI acquired pelvic image by DICOM viewer is converted to BMP format, and a total of104images was obtained. The bone tissue was segmentted by photoshop7.0image processing software and saved in BMP format.4. pelvis three-dimensional reconstructionThe image was input into the mimics software and the pelvis three-dimensional model was reconstruted after adjusting the threshold. Then we using smooth function to smooth processing of the model so as to strengthen the true sense and three-dimensional sense.Section2:resultsAll or most of the structure of the pelvis was reconstructed based on VCH-F1data set, CT and MRI database. We found that the digital three-dimensional model based on milling images data and CT database was similar by contrasting the three models and the reconstructed model had smooth edge and strong sense of three-dimension. Among the three models, the model based on CT database is the most realistic, and the model based on MRI database has bigger differences with milling images database for being more rough and having more subtle defects.Section3:disscussionThe models reconstructed by the three data set has obvious difference, and the principal reasons are as the following:l.the milling images database is the most authentic dababase, but the the reconstruction process is influenced easily by human factors, and can not be used in living and model is only for control;2. CT scanning on bone tissue showed better resolution, more clear, thus can be reconstructed using all the best software and the reconstruction method is relatively easy to grasp; MRI on bone tissue showed poor and image reconstruction technique is mainly manual segmentation, influenced more by subjective factors and imaging quality, without specific pelvic imaging scanning method and sequence. Thus, the model reconstructed is very rough and is quite different from from the pelvis invivo. So reconstruction method must be improved.Part2:the study of digital three-dimensional reconstruction for normal female pelvis invivo based on CT databaseChapter1:digital three-dimensional reconstruction andmeasurement for normal female pelvis based on CT database.The pelvis based on CT database is integrity and vivid, and is the ideal model for providing the clinical study of pelvic morphology and measurement of diameter. But The pelvic diameter that the routine measurement software Mimics can measure is limited. The entrance of the sagittal diameter of the pelvis, posterior sagittal diameter and diameter can not to be measured, and the pubic arch angle measurement has accuracy problems. So we apply the pelvic cutting software Geomagic software and measurement software UG into our study and successfully measure all the linear and angular.Section1:data collection1. data sourceWe select a case of patient who undergo pelvic CT scan. Patient’s basic information:51years old, Cantonese, height164cm, weight68kg, pregnancy2and birth2(all normal delivery), pelvis, without trauma history of spine and lower extremities, no history of pelvic operation and the clinical diagnosis is cervical cancer.2. equipment and software Siemens dual-source CT3.0, Mimics10.01reconstruction software, Geomagic software, UG software.3. data collectionThe patient is in abdominal scan position when scanning. The average scanning thickness is5mm, and the layer spacing is5mm. The scanning scope range from third lumbar vertebra margin to the ischial tuberosites. We segment the image thickness into1.0mm after scanning, a total of406layers and then disk storage.4. pelvic three-dimensional reconstructionThe original images were directly input into the mimics10.01software. The reconstruction threshold of the bone tissue was set from168Hu to1539Hu after the image positioning, image orgnizing and interpolation processing. Then the female pelvic model, including parts of lumbar spine and femur, was reconstructed by regional growth after the layer of bone tissue surface contour was generated.5. pelvic segmentationWe input the entire pelvic STL file into the Geomagic software, and save the right half side of the pelvis after select and delete the left half side of the pelvis by the plane cutting fuction.6. pelvic measurementWe totally measure14diameters and angles based on the digital three-dimensional model of the whole pelvis and right half side of the pelvis, including transverse diameter of pelvic inlet, conjugate of the inlet, Posterior sagittal diameter of inlet, The inner diameter of sacral shame, bi-ischial diameter, conjugate of the midpelvis, Posterior sagittal diameter of midpelvis, intertuberous diameter, conjugate of outlet, Posterior sagittal diameter of outlet, Symphysis pubis sacrum sacral curvature, height, length, pubic arch angle. The measurement data is in milimeter, and reserve to3decimal places. Section2:resultsReconstruction and measurement of the three-dimensional model of the female pelvisWe can not only reconstruct the whole pelvis based on the CT raw database, but also can reconstruct partial pelvic structure, such as left and right side of the pelvis. The morphology of reconstructed female pelvis and lumbar verterbral body is clear, and the morphology of the hip bone is clear and regular; sacral surface is smooth, and the curvature is natural. Bilateral sacral foramina are visible; Coccygeal morphological is integrity, and sacroiliac joint, sacrococcygeal joint and the pubic symphysis is legible. The model can be arbitrary scaling and rotation, and can export in the format of image and animation. The format is universial and convenient for further processing.Mimics and UG software can be used for three-dimensional measurement based on the model and can automatic generate the result of the measuring diameters and angles. The result can be accurate to0.01mm and0.01degrees. We can measure all the pelvic diameters and angles based on the whole pelvic model and the half side of pelvic model, and the procedure can be repeated countless times.Section3:discussionThe data for pelvic three-dimensional reconstruction based on CT scanning is in vivo. The three-dimensional model reconstructed can not only be free to zoom and rotate in any angle, but also be used to measure relative diameters and angles. This procedure reduce the effect of human factors, and can truly reflects the physiological condition of the pelvis. The three-dimensional reconstruction and measurement can be underwent in ordinary computer, convenient in clinical application to establish individualized virtual pelvic and can provide technical platform for related research. But the application in the maternal is restricted for the presence of radiation. Chapter2:CT-based3D pelvimetry:an analysis of289casesTo understand the changes in China’s normal female pelvis, on the basis of previous study of coporse study and three-dimensional techniques, we further use CT reconstruction and improved measurement technology to study in vivo Chinese normal Han women’s pelvis measurement, and data was compared with previous study for analysis.Section1:materials and methods1. Objects:subjects were required more than25years old, born and grew up in south China, with normal development of limbs, and without pathological pelvis, and having at least once natural vaginal delivery history. From December2009to December2011, a total of311female were involved in this study, all pelvis were measured with13diameter and angle measurement in three level. The subject were divided into three group:the youth group (25to40years old), middle-aged group (41to50years) and old age group(>50years old).2. Software and equipment, three-dimensional reconstruction and measurement method:the same with CT.3. Statistical methods:Pelvimetry data were obtained and were analyzed using SPSS13.0software. Groups were compared using independent two-sample paired t-test, linear correlation coefficient analysis, P value<0.05was considered statistically significance.Section2:Results1.Each value of the diameters of the different age groups are compared. Significant difference were found in these diameters:the entrance diameter, the entrance of the anteroposterior diameter, the inner diameter of sacral shame, pubic arch angle, pubic symphysis, sacrum curvature.2. pelvic diameters and age-related analysis Our group at the same time the pelvic diameters and age, correlation analysis, found the following trends:the entrance diameter and the pubic symphysis height increases with age, the sagittal diameter of the entrance after entrance of the anteroposterior diameter of sacral shame diameter, export transverse diameter of the pubic arch angle, sacral curvature decreases with an increase with age.Section3:DiscussionAge segmentation were relevant with Wang’s over50years ago, the old age group was equivalent with the subjects in Wang’s study. According to the laws of human bone development,25year old pelvis development basically stopped. The youth group could be considered to grow and develop in the reform and opening up and economic conditions change, which should be well present of modern pelvis of China.Among the three groups were compared, we found that the pelvic inlet plane diameter are becoming narrow, The pelvic inlet diameter, the sagittal diameter of the sacral shame, and diameter before and after increase with age. These data show the shape of modern female pelvis are becoming a long oval, the front of the narrowing of small change rear bigger or the front, the back of relatively large trend.Middle level and the outlet of female pelvic did not show too much change, pubic symphysis height shows a significant reduced trend. Sacrum length shows a smaller trend. These result indicates that the pelvis becomes shallow. At the same time, youth group’s sacrum shows an obvious curvature increase coccyx warp. These changes suggested that the pelvis of the modern Southern women in the entrance plane and the pelvic depth of change is more obvious, but is temporarily unable to come to the conclusion whether it is conducive to vaginal delivery.This study has some limitations. Most notably can’t compared with Wang’s study for measuring method. If this study would perform in a more large group of people, the conclusion maybe more convincible.Part3:the study of digital three-dimensional reconstruction for normal female pelvis invivo based on MRI databaseChapter1:The study of the MRI imaging sequence for digital three-dimensional reconstructionBecause MRI reconstruction is more difficult, there is few report on MRI-based reconstruction of a complete pelvic. In this research, we obtained ideal pelvic MRI imaging sequence from experimental screening on the tradition of pelvic MRI imaging sequences. Then we futher studied the parameters of the sequence obtained in the previous study, and obtained the best parameters.Section1materials and methods1. Data collectionFrom the patients with various gynecological diseases who were examined with pelvic MRI in our hospital from October2010to October2011, we choose20patients without trauma history on pelvis, spine or lower limbs anut pelvic operation history as the research objects.12of20patients were assigned to compare the pelvic MRI imaging sequences, and others to choose the best parameters.2. The pelvic MRI imaging sequence screeningAs the international reference information is lacking, we select4kinds of common MRI scanning sequence and parameters to do a control study, to obtained the ideal MRI scanning sequence.3. Optimize scanning parametersAfter choosing the best pelvic MRI imaging sequence, we further adjust the scanning parameters based on8patients. Section2:results1. The MRI images of different pelvic MRI imaging sequenceT2W1was the ideal scanning sequence to three-dimensional reconstruction offemale pelvic model from comparing the T1W1, T2W1, and PDW1.2. The best scanning parameters of T2W1FSE-T2WI axial thin slice scan with no fat saturation as an ideal scanning method is obtained.Section3:conclutionWe found that FSE-T2WI axial thin slice scan with no fat saturation is an ideal scanning method. That does the groudwork of MRI-base three-dimensional reconstruction of female pelvic model and pelvicmetry.Chapter2:digital three-dimensional reconstruction and measurement for normal female pelvis based on MRI database.Based on the modified of pelvic MRI imaging sequence, we reconstructed the digital three-dimensional female pelvic model. That provids a new method to study the female pelvis.Section1materials and methods1. Data collectionBased on the2sets of ideal datas in the previose study,4patients accepted MRI scaning use the choice scaning sequence and parameters. So we obtained6sets of ideal MRI datas.2. Three-dimensional reconstruction of female pelvisAfter importing the original images into Mimics10.01,three views of coronal, sagittal and axial planes were generated through automatic orientation, organization and interpolation processing Adjust the brightness and contrast of two-dimensional images, through threshold segmentation (thresholding) setting bone tissue threshold value for1250Hu-4095Hu, the software will automatically generate the layer mask, correction of bony tissue, make up for the lost pelvic signal. Finally, using region growing, edit mask and smoothing calculated3D female pelvis model which contains parts of lumbar spine and femur.3. Three-dimensional pelvimetryUsing the same measurement method fumbled in the CT reconstruction experiment, successfully measure12lines and2angle,which their numerica units are mm and are accurate to3decimal places.Section2:resultsWe successfully constructed three-dimensional model of the female pelvis. Compared with foreign research reports, the pelvis model has the merits, such as intense stereoscopic sense, intact and clear subtle structural, smooth surface, natural shape, repetitious measurements etc.Section3:conclutionMRI-based three dimensional reconstruction of3D pelvis based can avoid the impact of X-ray radiation on mother and fetus. The pictures and animation format saved on a regular computer in BMP and AVI formats are convenient for clinical use and can provide a new thought and method of pelvimetry in obstetric clinical application.Chapter2:digital three-dimensional reconstruction and measurement for normal female pelvis based on MRI database.1patien accepted MRI examination and CT examination. Then the digital three-dimensional reconstruction and measurement were made respectively based on MRI database and CT database to check the feasibility of digital three-dimensional reconstruction for normal female pelvis based on MRI database.Section1materials and methods 1. Data collection1patien without trauma history on pelvis, spine or lower limbs and without pelvic operation history accepted MRI examination and CT examination.2. Three-dimensional reconstruction of female pelvisDigital three-dimensional reconstruct the normal female pelvis based on MRI database and CT database respectively used the method as previously.3. Three-dimensional pelvimetryUsing the same measurement method fumbled in the CT reconstruction experiment, successfully measure12lines and2angle of the MRI medol and the CT medol, which their numerica units are mm and are accurate to3decimal places. Compare the values of the above14parameters in the same pelvis construction from CT and MRI.Section2:resultsCompared with the pelvis based on CT database, the pelvis model based on MRI database has some shortages, such as rough surface and not natural shape, but it still can provid the all3D pelvis shape. On the other hand, there are not obviously differeces in the measurements.Section3:conclutionThe MRI-based three dimensional pelvis medol is about the same as the CT-based three dimensional pelvis medol, so we can use the MRI-based3D pelvis medol replace the CT-based one, for avoiding the impact of X-ray radiation on mother and fetus. So the digital three-dimensional reconstruction and measurement for normal female pelvis based on MRI database can provide a new thought and method of pelvimetry in obstetric clinical application. 1.To investigate the methods of reconstructing the three dimensional digital woman pelvic model by using the data from serial section, CT scanning, MR scanning of the Virtual Chinese Human NO.1Female (VCH-F1). By comparison, we found that the model reconstructed by CT data had the best authenticity and integrity but the lowest difficulty of reconstructing technology. As a result, it’s suitable for clinical research. The three-dimensional model reconstructed by MR data was a little rough. There were coloboma in many minor areas. At the same time, the reconstruction was difficult. For the above reasons, we need to grope the better scanning conditions and reconstructed methods for clinical application.2. We successfully constructed the in vivo digital pelvic model basing on the CT scanning data, and explored the methods to measure the relevant dimensions and angles of pelvic model accurately by using Mimics, Geomagic and UG software. The three dimensional reconstruction and measurement could be carried out directly on the common computers. It was convenient for clinical application to rebuild the individual virtual model, which was the ideal model for studying the pelvis. But because there was X-ray radiation during the CT scanning, it was limited the application on pregnant woman.3.289integrity pelvis models were constructed based on CT data. After that we measured the models and statistical analysis by grouping. Then we found the changing trends of entrance plane of modern southern female pelvis changed from horizontal elliptic to longitudinal elliptic. Besides, the pelvis became shallow. This study provided an idea to further research the relationship between the changing trends of Chinese modern female pelvis and the parturition.4. After comparing, screening and adjusting the parameters, we determined the optimal scanning sequence. We found fistly that FSE-T2WI axial thin slice scan with no fat saturation is an ideal scanning method for digital three-dimensional reconstruction for normal female pelvis based on MRI database.5. We made a breakthrough to construct the the digital three dimensional femal pelvis and measure the dimensions and angles. All of these would provides a platform for the practical application in the obstetric pelvis research. The model has clinical value.